1. Field of the Invention
This invention relates to a circular knitting machine for producing a knitwear with selectively different characteristics, comprising a control device having a keyboard, a display unit and a memory for data pertaining to the knitwear and a plurality of components in the form of a cam arrangement with individually adjustable cam parts forming knitting points, a central adjusting device for simultaneous adjustment of a loop size at all knitting points and a yarn a feed device having positive yarn feeds rolls associated individually with the knitting points and at least one drive device for these rolls adjustable to a selected yarn feed amount.
2. Description of the Prior Art
Circular knitting machines of this kind as a rule comprise adjustable and/or interchangeable cam parts forming individual knitting points, in order to be able to produce knitwear with different knitting structures or knit patterns (e.g. DE 39 37 93 C2, DE 40 12 204 A1, DE 42 40 037 A1). Moreover lowering (drawn-down) cam parts are provided for adjusting the stitch size to meet requirements and can be individually adjusted to a selected lowering depth with the aid of adjusting bolts or the like mounted rotatably in the cam supports. Alternatively or additionally, a central adjusting device can be provided, with which the axial position of a knitting needle carrier, e.g. a needle cylinder, can be suitably altered relative to a knock-over edge or relative to another knitting implement support, e.g. a dial or a sinker ring (e.g. DE 26 31 858 A1, DE 32 32 643 A1, EP 0 652 314 A1). The cam parts as a rule have to be adjusted manually, while the central adjusting device is mostly provided with an automatic drive and can be adjusted by means of the input keyboard of a control device of the circular knitting machine.
The yarn feed to the individual knitting points is effected in the circular knitting machines initially referred to with positive yarn feed devices, since contrary to Jacquard machines the amount of yarn or the yarn length consumed at any knitting point per revolution of the needle carrier or cam arrangements is always exactly the same. The yarn feed devices are mostly driven by a common drive belt, which is for its part driven by a drive roller with variable diameter, in order to be able to select the amount of yarn supplied in accordance with requirements (e.g. DE 39 31 997 C2, DE 197 33 266 A1), while the alteration of the diameter of the drive roller can be effected manually or automatically through the keyboard of the control device. In order to measure and/or check the set yarn amount and/or the yarn tension resulting from this, there serve for example manual measuring rollers or measuring rollers mounted on the circular knitting machine and associated with at least one selected yarn (e.g. DE 24 36 401 A1, DE 38 27 453 C1) or feelers (DE 20 12 08 A1, DE 34 31 743 C2). It also known in this connection to control or regulate the amount of yarn which is fed in dependence on a measured value, e.g. the yarn tension, in that the transmission ratio or diameter of the drive roller is suitably acted on for example (e.g. DE 28 20 747 A1, DE 197 33 263 A1).
Knitting machines of this kind and their components described above make it possible to make the same kinds of knitting structures with different parameters (e.g. diameter of the needle cylinder, gauge or needle spacing), furthermore with different yarns, i.e. kinds of yarn or yarn thickness, and/or with different qualities, where as a rule and hereinbelow "quality" is understood as the weight of the knitwear per unit area, especially per square meter, called the square meter weight. If it is assumed, in order to simplify the understanding, that the machine parameters in a selected circular knitting machine remain unchanged, the characteristics of the knitwear produced on a circular knitting machine are thus described or defined essentially by the features of knitting structure, type of yarn, yarn thickness and quality.
In order to carry out a knitting order in a knitting factory, after selection of the knitting machine, the knitting structure and the yarn, it is necessary on the one hand to mount or adjust the cam parts at the knitting points in question adapted to make the selected knitting structure, on the other hand so to adjust the abovementioned and possible numerous further components (e.g., fabric spreaders, fabric take-down devices, etc.) that knitwear results whose quality corresponds as accurately as possible to the order.
Although the machine parameters, the yarn, the knitting structure and the quality are fixed by the order, such adjustment of the circular knitting machine has till now been a troublesome and time-consuming operation, which requires a great deal of experience of the operator. A main reason for this is that the single value to be set, namely the quality, is given in units appropriate to the person giving the order, namely the square meter weight of the knitwear, which can neither be accurately preset by adjustment of the components nor measured during the knitting process. It is indeed generally known that the quality can also be defined in units which the operator of the circular knitting machine needs for adjustment of say the yarn feed device and the take-down device, namely the yarn length to be fed per revolution of the needle cylinder or fed to the cam system and/or the number of loop rows per centimeter in the finished knitwear and that these values have a defined relationship with the square meter weight. It is further known that an increase in the yarn length per revolution (or per selected number of knitting needles) leads to the loops becoming larger and thus the square meter weight and the number of rows of loops per centimeter becoming smaller. Conversely, a reduction on the yarn length per revolution results in a reduction of the loops and thus an increase in the number of loop rows per centimeter and in the square meter weight. Finally, it is known that only the yarn length per revolution can reliably be adjusted, namely with the aid of the yarn feed device components, and the number of loop rows per centimeter and the square meter weight have to be found by trial. However, up until now, there has been no usable mathematical description for these characteristic properties, i.e. it is not possible to compute the yarn length per revolution and/or the number of loop rows per centimeter directly from the square meter weight or vice versa.
On account of these circumstances, the quality of knitwear has been described until now by the square meter weight, which is particularly important to the person giving the order. As a result, the operator begins the adjustment of a circular knitting machine as a rule by mounting the cam parts and assignment of the required yarns and yarn feed rolls to the various knitting points, while following this he estimates what yarn lengths per revolution are required for the various knitting points or how large the lop count per centimeter can be, which is important for the take-down device, on the basis of the prescribed square meter weight. On the basis of these estimates the lowering depth of the lowering cam parts, the central adjusting device, the yarn tensions, the take-down device and other possibly present components are then adjusted. When all adjustments have been made, a sample is made from knitwear produced with these adjustments and tested by weighing the sample to see whether the required square meter weight results. If this is not the case, the described adjustments are altered as often as needed to get the desired square meter weight or less by chance.
The described adjustments of the various components are partially facilitated in modern circular knitting machine in that they can be effected e.g. by electro-mechanical, electromagnetic, pneumatic and/or hydraulic means from the control panel of a customary control device and can be entered by means of a keyboard. However, this does not alter the fact that the operator is forced in implementing any order to repeat or change the described adjustments as often as is required for the knitwear to have the prescribed quality.
Against this background, the invention is based on the object of so designing the circular knitting machine described above that the time and the number of steps to be carried out for adjusting the components is reduced.
A further object is to simplify and speed up the method of adjusting of the various components of the knitting machine.
Yet another object of this invention is to standardize the steps for adjusting of the various components.
A further object of this invention is to design the knitting machine and its control device such that adjustment data sets associated with knitwears having preselected characteristics and arising from experience can be used for adjusting the various components of the knitting machine.
These and other objects underlying this invention are solved with a knitting machine the control device of which is arranged for entry and storing and for output and display of a plurality of adjustment data sets for the components, wherein each adjustment data set leads to knitwear with predetermined characteristics.
A method of adjusting a circular knitting machine in accordance with this invention is characterized in that a basic adjustment of the circular knitting machine is first produced using the machine adjustment data supplied by the control device, the square meter weight of the knitwear arising with this basic adjustments determined and a fine adjustment of the circular knitting machine is effected in the event of deviation from a prescribed square meter weight, until the quality of the knitwear corresponds substantially to the prescribed square meter weight.
The invention is based on the consideration that, with the manufacturer of a knitting machine and also in a knitting factory, numerous tests are made and orders met, which lead to adjustment data for the various components which is mostly troublesome to acquire but is very accurate. According to the invention this adjustment data arising from experience is used and so entered in a memory associated with the knitting machine in question that any knitwear with predetermined characteristics has its own associated adjustment data set for the various machine components. The operator can refer back to already existing adjustment data when meeting an order. Since this has provided to be correct in previous knitting processes, the operator can arrive at the right adjustments comparatively quickly. Moreover it is possible to make the once determined adjustment data sets available to all circular knitting machines of the same type. If no adjustment data set is available for any knitting order, the operator can start from an adjustment data set which has been obtained in the production of knitwear which comes closest to the knitwear to be produced. If this data set leads to knitwear which differs from the knitwear specified in the order only in the quality, this can mostly be altered to the desired value comparatively quickly using the central adjusting device. Added to this, it would naturally also be possible to store and use adjustment data sets which can be derived not directly from knitting processes already carried out but from other knowledge.
Further advantageous features of the invention appear from the dependent claims.